If the postwar period was called the "age of anxiety" and the 80s and 90s the "antidepressant era", we now live in bipolar times. A diagnosis that once applied to less than 1% of the population has risen dramatically, with almost 25% of Americans and around 5% of people in the UK estimated to suffer from some form of bipolarity.

Celebrities such as Catherine Zeta-Jones, Adam Ant and Demi Lovato speak of their bipolar conditions, and memoirs and self-help books flood the marketplace. CIA agent Carrie Mathison in Homeland and ex-teacher Pat Solitano in Silver Linings Playbook are portrayed as bipolar, and it even receives a mention in Scooby Doo.

As the old category of manic-depression was eclipsed by the new bipolar diagnosis, the latter generated ever more variations and subtypes: bipolar 1 was followed by bipolar 2, 2.5, 3, 3.5, and so on. A lowering of diagnostic thresholds and an increasing emphasis on mood fluctuations means that more and more people can be caught on the bipolar compass.

But recent debates that focus on quantitative factors such as how many days a person needs to be high or low to qualify as bipolar miss the point. Early research involved listening to what the patient had to say. There was an effort to move beyond the vagaries of mood swings and surface behaviour to find the latent motifs of manic depression and to investigate its differences from other diagnostic categories.

As many currents in mainstream psychiatry encourage an irresponsible blurring of these categories, it is the writers of first-hand accounts who bring us back to the original project of exploring individual experience. Rather than buying into the expanding maze of bipolar diagnoses, we need to return to the old category of manic depression and learn what is really at stake. Memoirs by Andy Behrman, Terri Cheney, Stephen Fry, Kay Redfield Jamison, Lizzie Simon and others pose a serious challenge to today's diagnostic laziness, as well as inviting us to rethink the phenomena of manic depression.

The analysis that we need has moved from medical journals to the testimonies we find with more and more frequency in our bookshops. Take mania. A manic person may spend vast sums of money on clothes, property, artwork or objects that they later look at quizzically. Fortunes can be squandered on what seem to others like idiosyncrasies. Why has the person bought those specific things? And why have they created a debt before the eyes of families and friends? To reduce mania to a purely biochemical aberration or to ask only how long the spree lasted will not help us here. These sprees are often equated with selfish, narcissistic rampages showing no regard for those who have to pick up the bill afterwards. Yet the more we listen to accounts of what has happened, the more we realise that often altruism is at play.

A man visited me for a first consultation in a manic state. When I opened the door, he immediately handed me a cheque, informing me that he had to dash off to meet someone so couldn't stay, but here was the fee, which, as he found too low, he'd multiplied by 10. I never saw him again, but his wife phoned to make sure I didn't cash the cheque.

The actor Vivien Leigh would have to be kept away from fancy stores such as Cartier and Asprey's during her episodes, yet her spending was on gifts for her cast and crew. One of my patients, zigzagging round London during a manic episode, heard the troubled tale of a minicab driver, and, redirecting the car to his bank, gave him his life savings there and then, "out of compassion".

The projects undertaken by a manic person may revolve around helping others, the righting of wrongs, or some act of protection. The clinical psychologist Kay Redfield Jamison reports her purchase of all the snakebite kits she could lay her hands on, with the aim of alerting the world to the proliferation of killer snakes in the San Fernando Valley. She explained: "I was doing all I could to protect myself and those I cared about". And Spike Milligan was celebrated for trying to protect not only the world's endangered wildlife but even the trees in his neighbourhood.

The manic person will often try to sweep other people up into some scheme or project, frequently with success. This is less about a private enterprise or solitary pursuit than a larger, more encompassing endeavour, frequently with a social good as its goal. However egotistical the person's actions may seem, there is an ideal on the horizon.

Jamison helps us to unravel this. Right at the start of her memoir Unquiet Mind she identifies the formative moment of her childhood. She is playing outside when a jet at the military base where they are living spins out of control directly above her. The pilot could have ejected and saved himself, yet instead chose to steer the aircraft so that it crashed beyond their playground.

This scene kept returning to haunt her, and although it certainly presents what might be interpreted as a child's first encounter with death, it also introduces the notion of sacrifice. The pilot gave up his own life to save others, and in doing so, created a debt. The importance Jamison gives to this scene is telling – one owes one's life to someone else.

Stephen Fry describes a similar logic in The Fry Chronicles when he writes that he owes his life to sugar. His grandfather was an expert on the cultivation of sugar beet, and in the late 1920s the British government invited him to move from Hungary to Suffolk to oversee domestic production. The relocation saved his life: the family who remained was wiped out by the Nazis. Fry connects his later addiction to cocaine to this attachment. A chain led from sugar to sweet cereal and candy and then to another white powder, cocaine, that would play a large part in his life. The key signifiers governing his behaviour were predicated on an original debt, linked to his grandfather.

The manic person might in her behaviour be showing her perception of being in debt, and the altruistic side of her manic episode might be an attempt to cancel the debt. A patient of the psychoanalyst Abraham Brill described his manic high in terms of exactly this cancellation: "I became very buoyant. All sense of responsibility seemed to leave me, and I felt very free and happy." All his life he had felt constrained and enslaved by conditions and circumstances, yet now he was "reborn into another life", another world in which people were different from how they had been before.

Brill's patient had been held responsible for the death of his younger brother as a child. Their sister had been trying to fry an egg in the hearth, a fire had started, and the boy died in the blaze. Their mother had blamed the patient for not having been there to protect his sibling. His mania was triggered after a work accident in which his arm had been crushed; it later had to be amputated. As he looked down at the limp limb and mangled fingers he had a strange dissociation. "That fellow is pretty badly smashed up," he thought. Before the mania itself began, he added, "My mind was myself and the hurt fellow was like a weak brother that in some way I was partly responsible for."

This question of debt may lie at the heart of manic depression. If there is an effort to do good, to protect others and to keep them safe, isn't there also a problem of responsibility? Fry owes his life to sugar and to the grandfather who escaped the Nazis, but what about his grandfather's debt to those he could not save who were left behind? With Jamison, the pilot's act of sacrifice created a debt in those he had saved, one which may also have raised a question about responsibility for a death further back in her own family history.

In case after case, we find a dilemma about responsibility at the level of preceding generations. It is often the parent of the manic-depressive person who will have experienced the tragic loss of a child, a sibling or a parent, and the responsibility for this death remains unresolved. The guilt that cannot be assuaged for one generation will haunt the next.

This sense of debt and responsibility cannot be settled easily for the manic depressive. It crystallises neither as paranoia ("The other is responsible") nor as melancholia ("I am responsible"), seesawing instead between highs and lows. If responsibility departs in the mania, it returns with a vengeance in the depression.

Doesn't this also help us to explain the curious vacillations around the sense of identity in manic depression? One of the most frequently voiced questions is whether it is some kind of foreign body or in fact an intrinsic part of the self. Would the person really be themselves after a chemical excision of their mania? Do the highs and lows reveal or obscure who they really are? Should manic depression be seen as constituting or as compromising the self?

Not knowing whether the manias and depressions belong to us or not reflects the difficulty of not knowing whether the responsibility is ours or someone else's. And isn't the most common thought after a manic episode "What have I done?"

It is striking to hear from manic subjects how horrified they are when reconstructing what they actually did in their mania. Sexual encounters and propositions with the spouses or partners of one's best friends seem totally natural at the time, only afterwards taking on their full weight. Promiscuity in mania shows a temporary abolition of the barriers of guilt that regulate social relations. Seducing her best friend's boyfriend, Terri Cheney felt that "something was wrong here, terribly wrong, but what that thing was I just couldn't remember. He was gorgeous, I was available, what else mattered?" The debt to her friend was erased in that moment. In her memoir, Patty Duke writes: "When you're manic, there are no consequences".

When manic, Leigh would sometimes play a parlour game called "Ways to kill babies", in which her guests were invited to mime unusual ways to dispose of an unwanted child. Given her own history – in which there had not only been a stillborn child before her birth but twins after her who survived for less than a week – what could have allowed her to act out such fantasies so blithely? Was it not the idea of a temporary release from debt, from the question of responsibility for a death, which would only immobilise her when it returned later in her depressive phases?

If in mania the person has the joyous feeling of no longer being judged, of no longer being responsible, judgment returns in a powerful, shattering way in the depressions. Many manic-depressive subjects report turning over in their minds all the bad things they have done, even years previously, during their lows. Any event from one's life, however trivial or distant, can be recruited to add muscle to the condemnatory judgment.

The autobiographical work of writers such as Cheney and Fry show how the apparently arbitrary cycles of manic depression are never accidental. There is a difficulty when it comes to integrating history, as if the links to one's past cannot be meaningfully subsumed. And hence the apparently ahistorical nature of manic depression: the mood swings seem to come out of nowhere.

Medical staff with little time on their hands to explore the exact circumstances of the manic episode or the depression may opt for a purely pharmaceutical response. Fine‑tuning medication and finding the right balance of drugs might be crucial, but they risk eclipsing the other work that is necessary: the careful contextualisation of the changes that the person experiences during an episode.

If at times episodes can be correlated to anniversary dates – a black depression coming in, say, the month that one had lost a loved one many years previously – they can also trigger at moments when an element not easy to integrate surfaces in a person's life. This could be the rage towards a loved one that cannot be easily processed, or a reminder of guilt. There is a floating sense of responsibility, frequently for a death, that is summoned at such moments yet can never be entirely grasped or pinned down.

Might this suggest that the prevalence of so-called bipolarity today is not simply an artefact of the marketing of new diagnostic categories? We live in an age that pays lip service to history, yet which continually undermines the ties we have to the past. The narrative of human lives is more or less absent in healthcare economies, where symptoms are seen as problems to be treated locally, rather than as signs that something is wrong at a more fundamental level. If the constellation of the manic depressive includes a difficulty in integrating a part of his or her history, society's neglect of this dimension can only make things worse.

Is it an accident that electroconvulsive therapy, seen as the most extreme form of all treatments for manic depression, is essentially something that operates on human memory, a way to wipe out history? Instead of yet more bipolar diagnoses, we need to return to an earlier, more humane approach, one that offers a manic depressive person the chance to come to terms – however slowly, and however painfully – with their past.